MB-5403:bp: handle very early memcached shutdown
MB-5403:bp: handle very early memcached shutdown

If memcached shutdown is requested too early this will lead to
clock_handler not being set up. So actual shutdown will only happen
when some socket event happens which will cause event_hander to be
called which will exit event loop.

Original commit is: c8f5e90ff432d2f3b4db1991c403b8fa9824d284

Change-Id: Ia8f6d15779875ed230d85788434a0f28ea597838
Reviewed-on: http://review.couchbase.org/16631
Tested-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>
Reviewed-by: Dustin Sallings <1c08efb9b3965701be9d700d9a6f481f1ffec3ea@spy.net>

mrkwse/memcached,daverigby/memcached,owendCB/memcached,mrkwse/memcached,owendCB/memcached,cloudrain21/memcached-1,mrkwse/memcached,abhinavdangeti/memcached,jimwwalker/memcached,couchbase/memcached,daverigby/memcached,jimwwalker/memcached,jimwwalker/memcached,daverigby/kv_engine,cloudrain21/memcached-1,couchbase/memcached,abhinavdangeti/memcached,daverigby/memcached,owendCB/memcached,abhinavdangeti/memcached,daverigby/kv_engine,couchbase/memcached,cloudrain21/memcached-1,daverigby/kv_engine,daverigby/kv_engine,couchbase/memcached,cloudrain21/memcached-1,daverigby/memcached,owendCB/memcached,abhinavdangeti/memcached,abhinavdangeti/memcached,mrkwse/memcached